Diaphania nitidalis  (Stoll)

Cucumber moth (pickleworm)

General

• Tropical insect attacking many cultivated or wild Cucurbitaceae. Belongs to the order Lepidoptera and the family Crambidae.
• Observed in the open field as well as under shelters.

• Sensitive botanical family (s)

• Affected production areas :

• Organs attacked

Symptoms, damage 

• Symptoms :
  • Galleries dug by the larvae in the fruits; also consumes the flowers, leaves and stems.
  • The holes and galleries made in the fruit are gateways to various secondary invaders: fungi or bacteria.

• Signs : Presence of larvae on plants, in fruits, and in culture (figures 1 and 2).

• Possible confusion : With other moths like D. hyalinata 

Biology

• Development cycle : The female larvae can lay between 300 and 400 eggs on the growing parts of plants: buds, flowers, etc. 
  • The larvae hatch about 3 days after laying: 5 larval stages follow one another which feeds on the fruits, leaves, flowers and stems for about 14 days. The first larval stages are recognizable by black dots on the body, the last are rather beige and measure about 2.5 cm. .
  • Pupation usually takes place outside the fruit in folds of dead leaves and lasts about 12 days until the emergence of the adult.
  • The adults, butterflies, have wings that are partly transparent and tinged with a brown color on the border, with purple reflections. They are mainly active at night. Females produce a pheromone which attracts males for mating.

Protection

• Weed the crop and its surroundings.
• Produce the seedlings in an nursery insect-proof .
• Check the sanitary quality of the plants before and during their introduction into the crop or shelter.
• Install  canvases  insect-proof in the nursery, on the rows in the open field when planting, and at the openings of shelters when weather conditions allow. During flowering the nets will be removed to allow pollination of the flowers. Pollinators can optionally be introduced under the nets to allow good fruiting while protecting the crop throughout its cycle.
• Install pheromone traps outside the shelter. (1)
• Favor natural enemies in field crops or under open shelters (2).
• Use biopesticides (3).
• Reason the  chemical protection that is possible for this use. Remember to respect the conditions of use of phytosanitary products. 

(1) In order to detect the presence of adults in the culture early, pheromone traps can be placed in the culture. However, the pheromones tested in Guyana did not reveal good trapping efficiency. Since giraumons and squash are very sensitive to cucumber moths, they can serve as indicator plants for the presence of moths.

(2) Natural predators such as Hymenoptera Vespidae and hoverfly larvae can attack the early larval stages of the cucumber moth. These naturally occurring auxiliaries can be favored by limiting insecticide treatments and by planting nectar-bearing plants near the plot. Ants of the Formicidae family are also excellent predators of the eggs of Diaphania sp.

(3) If the larvae are visible on the foliage, a preparation based on Bacillus thuringiensis var. kurstaki can be applied to the crop.